Park Tool CM-25 chain cleaner review

Ask any mechanic how to clean a chain and you’re sure to get a myriad of answers. Some suggest skipping the cleaning altogether, and just re-lubing and wiping. Others say an old paintbrush, degreaser, and a hose is perfect. The hardcore may suggest removing the chain completely and immersing it in an ultrasonic parts cleaner, parts washer, or bottle of degreaser.

And then there’s the chain cleaning tool.

Chain cleaning tools simply clip directly on to the drivetrain. As you backpedal, the chain is pulled through a bath of cleaning solution and series of rotating brushes. It’s a tool that’s long been popular – especially with home mechanics – for its ease of use and relatively good results.

I’ve tried many chain cleaning tools over the years, and while some have been better than others, I’ve managed to either break or wear out every single one of them – a feat that shouldn’t be so surprising when you consider that all of them have been made of plastic.

All, except for Park Tool’s CM-25 Professional Chain Cleaner.

The details

Launched at Eurobike in 2016, this die-cast aluminium chain cleaner has taken what has traditionally been a disposable consumer tool and built it for daily use. This tank of a tool opens on metal hinges and closes with a stainless-steel clasp, the optional (included) metal handle attaches with a small grub screw, and the whole thing is powdercoated in Park’s trademark blue paint. The powdercoat does chip if you drop it (a clumsy moment, but I’ll claim it as testing), but the metal case itself laughs off incidents that might otherwise shatter something made of plastic.

Inside, the CM-25 is basically identical to the Park’s plastic CM-5.2, featuring three counter-rotating brushes that scrub the chain on all four sides, and two sets of foam pads at the end of the case that help soak up excess fluid. All of that is contained in replaceable plastic cartridges that simply click into place inside the generously sized aluminium shell for easy replacement when needed. There’s also a small hole on top to add additional fluid once it’s closed, but otherwise, it’s a pretty pared back design.

Park Tool’s new CM-25 professional cleaner (right) next to the hugely popular CM-5.2 Cyclone cleaner.

All up, the tool weighs 464g – a hefty number if you’re one of the few to travel with tools. For comparison, the CM-5.2 is roughly half that at 242g.

The cleaning

Using the CM-25 couldn’t be much more straightforward: simply fill the case up to the bottom brushes with your degreasing solution of choice, clamp it onto the chain, back pedal until the chain is clean, and then rinse the solvent off.

Simple one-handed closure via a stainless steel latch.

Where some plastic alternatives are a fiddle to close onto the chain (these closing mechanisms are almost always the failure point, too), the Park’s hinge design simply shuts onto the chain and locks securely from there – all with one hand.

Park’s popular CM-5.2 tool was already my previous pick for chain cleaning tools, so it was no surprise that the CM-25 did an equally good job of scrubbing the plates and removing old grime and lube. It works exactly as intended, and if it doesn’t, I’d say try a different degreaser.

Speaking of degreaser, the CM-25 takes a fair bit of it. Park claim this as a feature, with more degreaser equalling a better clean. However, the obvious downside to the larger capacity is that you’ll go through that bottle of degreaser at a quicker rate.

One benefit of plastic designs is the translucent nature, which is obviously missing on the aluminium CM-25. Without this, it’s difficult to know just how dirty the degreaser inside is getting, or how much is left to keep the brushes wet. You get a decent sense of it by what the chain looks like, but it’s perhaps the only aspect of the plastic cleaners that I miss.

Hinging open, the CM-25 uses a series of rotating brushes to clean the chain, while the sponges serve more to soak up excess fluid to contain the mess.

Although the brush design works well at scrubbing the chain, and the row of sponges and pads at containing the mess, Park could could come up with a better way to hold the wicking pads inside the plastic cartridge addition. One of them would occasionally get pulled through the exit point of the cleaner with the chain – not a total deal-breaker, but certainly a nuisance.

Either way, removal and replacement of the cleaning cartridges is a breeze and it means the case should last practically forever. Such simple removal also means the smoothly coated metal case is simple to clean, in case you’re anal about keeping your cleaning things clean. The cartridges themselves aren’t all that cheap – about US$19 – but they last just as long as a whole plastic unit would and so replacement shouldn’t be all that regular.

A clean chain, at a price

Simply put, this is the best on-bike chain cleaning tool I’ve ever used, and dare I say it, the best there is. However, there’s one major caveat with that statement: price.

Yes, the Park CM-25 is a pro-level tool built to outlast any bike it’s cleaning, but with an official retail cost of US$99/AU$155, it’s a tough purchase to justify, especially when you consider that Park offers a more economical version that cleans just as well at a fraction of the price.

If you’re a bike mechanic and like regularly using a chain cleaning tool, you’ll appreciate the bin space this tool saves. And if you’re a rider that fancies using a chain cleaner and must have the best or just hate the idea of unnecessary plastic waste, this tool is for you. But for just about everyone else, buy the CM-5.2, or do as the race mechanics do – grab a paintbrush, a cut-off bidon, and get scrubbing.

Random Tip: To avoid getting degreaser inside of your rear hub bearings when cleaning your chain, get yourself a chain keeper that clips in place of your rear wheel. Some examples of this include Pedro’s Chain Keeper, Feedback Sports Chain Keeper, Park Tool’s Dummy Hub or Abbey Bike Tools’ TI Wash Buddy. Since writing this review, we conducted a group test of nine different chain keepers.

A large handle is comfortable to use and helps to create your hands relatively clean in the process.

Cleaner in action. Here you can see one of the wicking pads being pulled from the insert. It’s a small detail, but I wish there was more holding this pad in place.

Hinging open, the CM-25 uses a series of rotating brushes to clean the chain, while the sponges serve more to soak up excess fluid to contain the mess.

A look inside the CM-5.2 Cyclone cleaner reveals it’s much the same cleaning layout as the new professional version.

A small grub screw holds the large handle in place on the CM-25.

Take the plastic cartridges out and you’re left with an empty shell. Note the smooth edges that make it easy to clean.

The cartridges are available as a replacement part. They unclip by hand without fuss.

Built to last, the aluminium construction doesn’t come cheaply.

No part of the metal casing comes into direct contact with the chain, leaving the plastic cartridges as the only wear items.

A closer look at the upgraded closure found on the CM-5.2 Cyclone cleaner. It’s a welcomed change from the previous version, but is still missing a few tricks compared to the CM-25’s single latch design.